The sealed beam headlamps that have been used in tactical military vehicles for many years exhibit poor performance characteristics when compared to current automotive lighting systems. A common headlamp used in tactical military vehicles is an incandescent, sealed beam headlamp. The MMPV (Medium Mine Protected Vehicle), as well as other military vehicles such as the HMMWV (High Mobility Multipurpose Wheeled Vehicle), currently use a headlamp that is interchangeable with a headlamp system specified in MIL-DTL-14465E (12 Aug. 1998), attached hereto, called a vehicular composite light assembly, including a first incandescent bulb lamp providing a high beam and a low beam, and a second incandescent bulb lamp also providing a high beam and a low beam, but covered by a filter so as to pass only infrared light. An operator switches from visible to infrared illumination, and thus engages one or the other of the bulbs, and then selects high beam or low beam, as needed. The headlamp system can be provided as a quick detachable or as a bolt-down model. (MIL-DTL-14465E indicates it is a specification for tracked vehicles, but the specification is also for headlamp systems used in non-tracked vehicles also). These headlamps produce on average up to 75,000 cd (candela), and 100 m (meter) visibility at 2 lx (lux). The color temperature for incandescent headlamps is about 3000 K, giving the light a warm yellowish appearance.
Military “blackout” operations present greater challenges: the vehicle must be operated at night at a moderately high speed without being detected by enemy forces. Traditional blackout lights deployed on tactical military vehicles provide a small amount of visible light illumination directly in front of the vehicle bumper. Many operators consider this ineffective especially when driving at higher speeds. Night vision goggles (NVGs) and infrared lighting significantly improve low-light and blackout operations, but NVGs used without providing any sort of illumination are generally considered inadequate for such operations.
The general consensus is that it is highly advantageous to provide infrared (IR) illumination in a field of view, rather than relying on infrared produced by objects in the field of view, as this dramatically increases the effectiveness of even lower-performing NVGs. IR illumination is often produced from an incandescent lamp using a blackout filter/lens that passes only IR radiation from the incandescent lamp. IR illumination produced in this fashion is inefficient, since the lamp still produces visible light, and only a small portion of the radiation produced by the lamp is passed as IR. Additionally, blocking all visible light is difficult, and the filter/lens must be mechanically moved into place, resulting in an unacceptable conversion time to switch between visible and infrared illumination mode.
What is needed is a headlamp that is economical, that provides both visible light and IR illumination, both of sufficient intensity for vehicle operation (at night) at reasonable speeds, with the ability to switch from visible to IR light in an acceptable time, and with a thermal management system and headlight aiming mechanism.